In line with the renewed World Health Organization Global Malaria Control Strategy, we have advocated the use of satellite imagery by control services to provide environmental information for malaria stratification, monitoring, and early warning. To achieve this operationally, appropriate methodologies must be developed for integrating environmental and epidemiologic data into models that can be used by decision-makers for improved resource allocation. Using methodologies developed for the Famine Early Warning Systems and spatial statistics, we show a significant association between age related malaria infection in Gambian children and the amount of seasonal environmental greenness as measured using the normalized difference vegetation index derived from satellite data. The resulting model is used to predict changes in malaria prevalence rates in children resulting from different bed net control scenarios.

Focal extracellular matrix degradation morphologically identified in human portal pipestem fibrosis due to Schistosoma mansoni did not express immunohistochemical reactivity for metalloproteinases (MMP-1, MMP-2, and MMP-9) and their inhibitors (TIMP-1 and TIMP-2). However, when active schistosomal periovular granulomas were present, a strong reactivity for MMP-1, MMP-2, TIMP-1, and TIMP-2 was observed. No reactivity was ever observed for MMP-9. However, the positive pattern of immunohistochemical expression was not seen in old fibrotic periovular granulomas, which were sometimes situated in other areas of the same microscopic section. Positive staining for MMPs and TIMPs was observed at the same time in hepatocytes and within the apical portion of bile duct epithelium. These findings are consistent with the concept that matrix degradation in recent and old fibroses, in addition to differing at the ultrastructural level, also differs in immunohistochemical expression of metalloproteinases and their inhibitors.

The parasitic helminth Onchocerca volvulus causes ocular onchocerciasis (river blindness) and onchocercal skin disease. To understand the immunologic basis for early stage skin disease, we developed a model in which C57B1/6 mice were immunized subcutaneously and injected intradermally (in the ear) with soluble O. volvulus antigens (OvAg). We found that ear thickness increased significantly after intradermal injection of OvAg and remained elevated for at least 7 days. Dermatitis was dependent on prior immunization, and was associated with an intense cellular infiltrate in the dermis. Neutrophils were the predominant inflammatory cells in the dermis 12 hr after intradermal injection, with only occasional eosinophils present. Conversely, increased ear thickness at later time points was associated with eosinophils, and neutrophils were only rarely detected. Both cell types were present at intermediate time points. These data indicate that recruitment of neutrophils and eosinophils to the skin is temporally regulated.

Aotus monkeys are good models for erythrocyte-induced Plasmodium falciparum and P. vivax infections and have been extensively used in malarial drug and vaccine development. Recently, it has been shown that certain species of Aotus can be infected with sporozoites, and that the degree of susceptibility varies among species. We demonstrate here that Panamanian Aotus lemurinus lemurinus are susceptible to a sporozoite-induced infection, opening the possibility that this species of Aotus could be used as models for testing the efficacy of pre-erythrocytic P. falciparum vaccines and drug candidates directed at the pre-erythrocytic stages of P. falciparum and P. vivax malaria. In this species, we compared sporozoite infection rates. Two of four animals splenectomized prior to infection with sporozoites developed patent parasitemias. Seven of eight animals splenectomized either 7 or 35 days after infection became parasitemic. Additionally, we used a P. falciparum-specific polymerase chain reaction (PCR) method to detect the early appearance of parasitized erythrocytes in the blood prior to detection by conventional microscopy, and found that the parasitemia was detected first in five animals by the PCR method, first in three animals by blood film, with one parasitemia detected simultaneously. We also demonstrated the feasibility of infecting monkeys located in Panama with sporozoites isolated at an insectary in Atlanta, thus documenting the feasibility of similar studies where the insectary and monkey colony are not in the same location. A subsequent attempt to infect these monkeys using sporozoites was not successful, suggesting that this model of human malaria is not yet ready for routine use in vaccine or drug efficacy screening. This model merits further study because of the importance of testing pre-erythrocytic P. falciparum malaria vaccines and drugs in animals.

Single doses (250, 500, 1,000, or 2,000 units/kg) of an ovine polyclonal-specific Fab fragment directed against tumor necrosis factor-alpha (TNF-alpha) were given to 17 adult patients with severe falciparum malaria immediately before treatment with artesunate in a pilot study to assess safety and optimal dosage with a view to future studies. Clinical and laboratory variables were compared with 11 controls. In the groups given Fab, there was a tendency for a faster resolution of clinical manifestations and reduction of fever but also a tendency towards longer parasite clearance times. Adverse events were more common in the control group and no early anaphylactic or late serum sickness reactions occurred in the Fab treated patients. On admission all patients had markedly elevated levels of TNF-alpha (85-1,532 ng/L) and interleukin-6 (IL-6) (30-27,500 ng/L). Also, 86% had elevated interferon-gamma (IFN-gamma) levels, 75% had increased IL-2 levels, 36% had increased IL-8 levels, and 21% had increased IL-1beta levels. Antibody treatment reduced IFN-gamma concentrations in a dose-related manner, but had no obvious effects on levels of other cytokines in this small study, although unbound TNF-alpha was undetectable after Fab treatment. Circulating concentrations of soluble E-selectin, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 were not affected by Fab treatment. The Fab exhibited a two-compartment, dose-proportional kinetics with an average elimination half-life of 12.0 hr, with about 20% being excreted renally. These results encourage a randomized, placebo-controlled trial in patients with cerebral malaria and provide some guidance about dosage.

We report a case of melioidosis with left adrenal gland abscess in a 51-year-old man from Taiwan who traveled to Rangoon, Burma for a four-day tour on July 15, 1997. The patient developed fever and left upper abdominal pain upon returning to Taiwan on July 19, 1997. Ten days after returning to Taiwan, he was admitted to Chang Gung Memorial Hospital in Keelung, Taiwan and blood culture on admission was positive for Burkholderia pseudomallei. Computerized tomography of the abdomen revealed left adrenal gland swelling and suppuration. Treatment with parenteral ceftazidime and cotrimoxazole for three weeks followed by two months of oral cotrimoxazole cured the infection. The patient remained asymptomatic at 12 months follow-up.

Helicobacter pylori is one of the most common human bacterial infections in the world and children in the developing countries acquire H. pylori infection early in life. We prospectively evaluated the prevalence of serum antibodies to H. pylori in a cohort of pregnant women and their offspring. Mothers' sera were collected during the third trimester of pregnancy and sera from their offspring were collected when they were 7-9 months and 18 months of age. Pylori-Stat, a commercially available ELISA kit, was used to detect antibodies to H. pylori in the serum of the subjects tested. Sera from 169 mothers were available for testing and 88% of these samples were positive for anti-H. pylori IgG. Of the 169 children tested, 13% of the infants 7-9 months of age and 25% of the children 18 months of age had serologic evidence of H. pylori infection. These data indicate that infection with H. pylori is common in Egypt and acquisition of infection occurs at a very young age.

A 26-year-old Brazilian man was admitted to The Toronto Hospital with a headache and visual scintillation. His last travel to Brazil was five years previously. A computed tomography (CT) scan of the head showed an occipital mass with surrounding vasogenic edema. Occipital brain biopsy revealed Schistosoma mansoni eggs. The patient was treated with two doses of praziquantel (20 mg/kg) and dexamethasone (10 mg). His symptoms and occipital mass resolved. Cerebral schistosomiasis is, in part, caused by the host's inflammatory response to Schistosoma. Modes of treatment have included surgical resection, the antiparasitic drugs oxamniquine or praziquantel, and corticosteroids. Corticosteroids may diminish granulomatous inflammation, thereby preventing further tissue destruction, and there is evidence that they also reduce ova deposition. Our review of the literature supports prompt medical therapy in patients with cerebral schistosomiasis. While the minimally or asymptomatic individual may be treated with praziquantel alone, clinicians should consider adjunctive therapy with corticosteroids for patients with prominent neurologic signs or symptoms or mass lesions with evidence of surrounding edema on a CT scan or by magnetic resonance imaging.

A case of infection with Gongylonema is described in a 41-year-old woman living in New York City. The patient sought medical attention with the complaint of a sensation of 1-year duration of something moving in her mouth. On two occasions she removed worms from her mouth, once from her lip, once from the gum. One of the specimens submitted for examination was an adult female Gongylonema. It is not possible to say whether the infection was acquired in New York City, or elsewhere, since the patient traveled frequently to Mississippi to visit relatives. As cases of delusional parasitosis continue to increase, clinicians and laboratorians alike need to be alert to the possibility that foreign objects removed from the mouth, or elsewhere, may indeed represent unusual parasitic infections, and that these objects should be examined before being discarded.

We initiated a longitudinal study of Bancroftian filariasis to improve understanding of dynamics and risk factors for infection in villages near Cairo, Egypt. Baseline prevalence rates for microfilaremia and filarial antigenemia for 1,853 subjects more than 9 years of age were 7.7% and 11.2%, respectively. Microfilaria counts, antigen levels, and microfilaremia incidence over a 1-year period were all significantly lower in older people. These findings suggest that humans develop partial immunity to Wuchereria bancrofti over time. One-year incidence rates for microfilaremia and antigenemia were 1.8% and 3.1%, respectively. Filarial antigenemia, IgG4 antibody to recombinant antigen BmM14, and household infection were all significant risk factors for microfilaremia incidence. Microfilaria counts and parasite antigen levels were significantly reduced by diethylcarbamazine therapy, but many infected subjects refused treatment, and most treated people were still infected one year later. Incident infections approximately balanced infections lost to produce an apparent state of dynamic equilibrium.

We carried out a serosurvey for cysticercosis among people visiting the Central Hospital of Maputo, the capital of Mozambique, between January and June 1993. A standardized questionnaire was designed to obtain information on demographic, socioeconomic, environmental, and behavioral characteristics related to the transmission of the infection. Four hundred eighty-nine individuals were tested for anti-cysticercosis antibodies: 222 blood donors and patients from the Department of Orthopedics, 148 patients from the Department of Neurology, and 119 patients from the Department of Psychiatry. The overall positivity rate was 12.1% (59 of 489). Anti-cysticercus antibodies was detected in 14.9% of the blood donors and patients from the Department of Orthopedics, 11.5% of the patients from the Department of Neurology, and 7.6% of the patients from the Department of Psychiatry. Living in poor sanitary conditions seems to be an important factor related to human cysticercosis in Maputo, Mozambique.

Isolates from 25 (13 sporadic and 12 outbreak) cryptosporidiosis cases, 24 of which were from British Columbia, Canada, were characterized using nested polymerase chain reaction amplification of the polymorphic internal transcribed spacer 1 locus. Two predominant Cryptosporidium parvum genotypes were found. Twelve (8 sporadic and 4 outbreak) isolates amplified with the cry7/cry21 primer pair and 12 (5 sporadic and 7 outbreak) isolates amplified with the cry7/cryITS1 primer pair. Multi-locus gene analysis using sequence polymorphisms on 3 other loci, i.e., the thrombospondin-related adhesion protein gene, the dihydrofolate reductase gene, and the 18S rRNA gene on 8 (4 outbreak and 4 sporadic) isolates showed non-random association among the human and animal alleles of the 4 different C. parvum gene loci. Associations between these 2 parasite genotypes and different routes of cryptosporidiosis transmission such as zoonotic, anthroponotic, and waterborne transmission were studied using municipal population and agricultural information, as well as detection of C. parvum oocysts in municipal drinking water specimens of the residential communities of sporadic and outbreak cases.

The causative agents of rickettsial diseases (Rickettsia conorii, R. typhi, and Coxiella burnetii) have been reported throughout the African continent. However, there have been no reports on epidemiologic surveys of these infections in Zambia. This study was designed to clarify the prevalence of three rickettsioses in 377 humans in Zambia. The seroprevalence of antibodies against R. conorii, R. typhi, and C. burnetii was 16.7%, 5.0%, and 8.2%, respectively. The rates of antibody positivity against R. conorii and C. burnetii were higher in the eastern (23.1% and 11.8%) and western (16.8% and 7.4%) areas of Zambia than in the northern (3.0% and 3.0%) area of this country. There was little difference among the three areas in the distribution of antibodies against R. typhi. Since cattle breeding is more extensive in the western and eastern areas than in the northern area, it is thought that cattle-breeding areas are foci of R. conorii and C. burnetii infections in Zambia.

The seroprevalence of Orientia tsutsugamushi, Rickettsia typhi, and TT118 spotted fever group (SFG) rickettsiae in 300 rubber estate workers in Slim River, Malaysia was determined in December 1996 and March 1997. In December, which was the wet season, 23.3%, 3.0%, and 57.3% of the population had antibodies detected against the three rickettsiae, respectively. The highest seropositive rate of 40% was detected for single infection with SFG rickettsiae, followed by a rate of 15.3% for both O. tsutsugamushi and SFG rickettsiae among the rubber estate workers. Subjects less than 21 years old had a lower seroprevalence of SFG rickettsiae compared with the other age groups. Indians had a higher seroprevalence of O. tsutsugamushi compared with other ethnic groups. Rubber tappers had a higher seroprevalence of SFG rickettsiae compared with other occupational groups. During the dry season in March 1997, there was a significant increase in the seroprevalence of R. typhi. The seroconversion rates for IgM against O. tsutsugamushi, R. typhi, and SFG rickettsiae were 5.7%, 12.3%, and 15.1%, respectively, during the four-month period. Significant variations of antibody titers towards the three rickettsiae was noted among subjects who were bled twice. This suggests a significant and continual exposure of rubber estate workers to the three rickettsiae.

Japanese encephalitis (JE) is an endemic disease in Taiwan. A mass vaccination program of children against JE was first implemented in 1968. Along with general improvements in various aspects of living conditions over the years, the program has brought JE well under control. The main characteristics of JE epidemiology in Taiwan in the past 3 decades are as follows. The transmission mode remains unchanged-that is, the amplification stage of the virus in pigs is followed by a human epidemic each year. The frequency of JE incidence has dropped significantly. The incidence rate of confirmed cases was 2.05 per 100,000 in 1967, the highest in record, and merely 0.03 per 100,000 in 1997. Confirmed cases occur sporadically all over the island. The peak of the epidemic season has shifted from August in the 1960s to June since the 1980s. The age distribution of confirmed cases has shifted gradually from mainly children to adults. Vaccine efficacy for those having received more than 2 doses of the vaccine is estimated to be about 85%.

To determine the prevalences of hepatitis B virus (HBV), hepatitis C virus (HCV), and human T lymphotropic virus type-1 (HTLV-1) infections in residents of the Solomon Islands, we surveyed 1,610 serum samples from 1,113 outpatients and 497 healthy volunteer blood donors at the Central Hospital in Honiara, the Solomon Islands. The prevalence of hepatitis B surface antigen (HBsAg) by radioimmunoassay (RIA) (n = 315, 19.6%) was significantly different from that of antibody to HCV (anti-HCV) by a second-generation enzyme immunoassay (EIA) (n = 4, 0.2%) and antibody to HTLV-1 (anti-HTLV-1) by an ELISA with Western blot analysis to verify the positivity (n = 49, 3.0%) (P < 0.0001, respectively). There were no significant differences in the prevalences of these markers between outpatients and blood donors. Hepatitis B e antigen (HBeAg) was detected by RIA in 130 (41.3%) of 315 HBsAg-positive samples. The distribution of HBsAg subtypes by EIA was 190 adr (60.3%), 111 ayw (35.2%), and 14 (0.4%) other subtypes. The HBeAg prevalence decreased with age in all groups for each subtype. There were no significant differences in the prevalence of HBeAg among HBsAg subtypes. We conclude that HBV infection is highly endemic in selected Solomon Islands populations, and that the high prevalence of HBeAg may be associated with the spread of HBV infection there.

This paper describes the isolation and partial genetic characterization of a hantavirus from a pygmy rice rat, Oligoryzomys microtis, collected within the urban area of Iquitos, Loreto Department, Peru. The virus, designated HTN-007, exhibited the highest degree of genetic similarity to Rio Mamore virus, which was originally described from the same rodent species in eastern Bolivia. Comparison of small and medium segment nucleotide sequence data from HTN-007 and Rio Mamore virus revealed 87% and 85% sequence identity, respectively. Based on these analyses, HTN-007 appears to be a variant of Rio Mamore virus. As such, it represents the first successful isolation of Rio Mamore virus and the first evidence for the existence of a hantavirus in Peru. Serologic studies done by immunofluorescence on blood samples of 56 O. microtis trapped at the collection site indicated that 21.4% had antibodies to hantavirus. In view of the proximity of this rodent species to humans and the close phylogenetic relationship of Rio Mamore virus to hantaviruses that have been associated with human disease, Rio Mamore virus may be a hantavirus of some public health importance in tropical South America.

To investigate the relationship between parasite prevalence and malaria-related morbidity, we carried out a comparative study among cohorts of school children from two villages, Dienga, Gabon, and Pouma, Cameroon, both located in malaria-endemic areas. Seven to 17 year-old children attending primary schools were similarly followed-up at each site to evaluate the frequency of malaria attacks. Follow-up involved daily temperature recording (and blood smears in the case of fever) and preparation of blood smears every two weeks. In Pouma, 186 children were followed-up for six months. In Dienga, 228 children were followed-up for nine months. The mean prevalence rate of Plasmodium falciparum infections (as assessed by the blood smears) was twice as high in Pouma compared with Dienga (45.2% versus 26.8%; P < 0.0001), whereas the monthly malaria attack rate (as assessed by the daily surveillance) was twice as high in Dienga compared with Pouma (21.5% versus 41.4%; P = 0.003). The possible implication of several parameters that may differ between the two areas, such as the malaria transmission level, the economical and social status of the inhabitants, the characteristics of infecting parasite strains, and the genetic background of the population, is discussed.